559 research outputs found

    A remark on the asymptotic form of BPS multi-dyon solutions and their conserved charges

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    We evaluate the gauge invariant, dynamically conserved charges, recently obtained from the integral form of the Yang-Mills equations, for the BPS multi-dyon solutions of a Yang-Mills-Higgs theory associated to any compact semi-simple gauge group G. Those charges are shown to correspond to the eigenvalues of the next-to-leading term of the asymptotic form of the Higgs field at spatial infinity, and so coinciding with the usual topological charges of those solutions. Such results show that many of the topological charges considered in the literature are in fact dynamical charges, which conservation follows from the global properties of classical Yang-Mills theories encoded into their integral dynamical equations. The conservation of those charges can not be obtained from the differential form of Yang-Mills equations.Comment: Version to be published in JHEP, Journal of High Energy Physics (19 pages, no figures, some examples added

    The integral equations of Yang-Mills and its gauge invariant conserved charges

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    Despite the fact that the integral form of the equations of classical electrodynamics is well known, the same is not true for non-abelian gauge theories. The aim of the present paper is threefold. First, we present the integral form of the classical Yang-Mills equations in the presence of sources, and then use it to solve the long standing problem of constructing conserved charges, for any field configuration, which are invariant under general gauge transformations and not only under transformations that go to a constant at spatial infinity. The construction is based on concepts in loop spaces and on a generalization of the non-abelian Stokes theorem for two-form connections. The third goal of the paper is to present the integral form of the self dual Yangs-Mills equations, and calculate the conserved charges associated to them. The charges are explicitly evaluated for the cases of monopoles, dyons, instantons and merons, and we show that in many cases those charges must be quantized. Our results are important in the understanding of global properties of non-abelian gauge theories.Comment: Version to appear in Physical Review D (46 pages, 3 figures, 1 table

    Impact of displacement demand reliability for seismic vulnerability assessment at an urban scale

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    This paper addresses seismic vulnerability assessment at an urban scale by focusing on the displacement demand determination for building damage prediction. The study is based on the comparison of urban seismic damage distributions obtained by the displacement demand computed using non-linear time-history analysis (NLTHA) with three simplified methods. These methods include the N2 method, the Lin & Miranda proposal and an optimized version of the N2 method. Comparing the different damage distributions from the three simplified methods with the one obtained by time-history analysis helps understanding the reliability of displacement demand determination. The study is carried out on Sion and Martigny, two typical Swiss cities. For the case of Sion, results clearly show that using N2 method may lead to significant overestimation of damage grade distribution. The use of Lin & Miranda method and optimized version of N2 improves the damage prediction in both cases. For the other studied case of Martigny, N2 method and Lin & Miranda proposal are not accurate. The optimized version of N2 method provides stable and reliable results

    Sorção, degradação e lixiviação dos herbicidas tebuthiuron e diuron em colunas de Solo.

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    Leaching potentials of three acidic herbicides were assessed for three different Brazilian soils, by means of the multi-layered AFi model. Values of AFi were also calculated for each herbicide using a modified model (AFi*), where sorption coefficient (Kd) values are pH-dependent. The pH-dependent Kd values estimated for all three herbicides were always higher than pH-independent Kd values calculated using average Koc data. The pHdependent Kd values for the three herbicides evidenced a large variation from layer to layer following changes in OC and pH for the different soil depths. When OC decreases, Kd tends to decrease; on the other hand, lowering pH tends to increase Kd. For all three soils, OC and pH exhibit an overall decrease with depth. Despite differences between the pH-independent Kd and the pH-dependent Kd values, the AFi values for 2,4-D, calculated by the original multilayered-soil model and by the modified model (AFi*), were similarly low for all three soils, mostly due to the short half-life of 2,4-D. The pH-dependent AFi values for flumetsulam were always much lower than values calculated by the original multi-layered model. Therefore, the pH-independent model appears to overestimate leaching potential of flumetsulam. The AFi values for sulfentrazone calculated by the original and the modified models were similarly high for all three soils, despite the differences in Kd values. The long half-life of sulfentrazone mostly contributed to the similar high values of AFi for the three different soils. Overall AFi values showed large differences for sulfentrazone when calculated by the original and by the modified model (AFi*), owing to its high AF value for each layer. Thus, the original AFi model would seem to markedly overestimate the leaching potential for sulfentrazone, as well as for flumetsulam for these soil conditions

    Monitoramento do risco ambiental de agrotóxicos: princípios e recomendações.

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    Uso de Agrotóxicos no Brasil. Princípios do Monitoramento de Risco Ambiental. Exposição Ambiental aos Agrotóxicos. Efeitos Ambientais dos Agrotóxicos. Plano de Monitoramento do Risco Ambiental. Procedimentos de Amostragem. Indicadores de Risco Ambiental. Recomendações Técnicas para Monitoramento do Risco Ambiental.bitstream/CNPMA/5810/1/documentos_42.pd

    Turbulent superfluid profiles in a counterflow channel

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    We have developed a two-dimensional model of quantised vortices in helium II moving under the influence of applied normal fluid and superfluid in a counterflow channel. We predict superfluid and vortex-line density profiles which could be experimentally tested using recently developed visualization techniques.Comment: 3 double figures, 9 page

    Movimento do herbicida tebutiuron em dois solos representativos das áreas de recarga do Aqüífero Guarani.

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    O movimento do herbicida tebutiuron foi analisado em um Latossolo Vermelho Distrófico psamítico (LVdq) e um Neossolo Quartzarênico Órtico típico (RQo), representativos das áreas de recarga do aqüífero Guarani no Brasil, tendo como fatores influenciadores, a condutividade hidráulica (K), o teor de carbono orgânico (CO) e o teor de argila (TAr). O presente estudo foi realizado em colunas de solos indeformados, com aplicação do produto comercial contendo o herbicida em discussão. Esses parâmetros evidenciam certa influência na movimentação vertical do herbicida tebutiuron, particularmente no RQo, uma vez que esse herbicida é quimicamente neutro. Observou-se, por exemplo, uma diferença significativa entre os valores K dos dois solos, sendo superior no RQo. Além de uma relação inversa entre teores de CO e de TAr e os valores de K dos dois solos, indicando serem aqueles parâmetros inibidores do deslocamento do tebutiuron no perfil do solo. Os resultados aqui obtidos neste trabalho visam subsidiar estudos de avaliação de risco ambiental, sobretudo água subterrânea, a partir de áreas de recarga de aqüíferos naturalmente frágeis, com ênfase para o aqüífero Guarani
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